Anode for a secondary, high-temperature electrochemical cell

Abstract

A high-temperature, secondary electrochemical cell includes an anode containing lithium, an electrolyte containing lithium ions and a cathode containing a chalcogen material such as sulfur or a metallic sulfide. The anode includes a porous substrate formed of, for instance, a compacted mass of entangled metallic fibers providing interstitial crevices for receiving molten lithium metal. The surfaces of the interstitial crevices are provided with a coating of cobalt metal to enhance the retention of the molten lithium metal within the substrate.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows: 
     
       1. In a secondary electrochemical cell comprising an anode containing lithium metal, a cathode containing a chalcogen material and an electrolytic salt between said anode and cathode, the improvement wherein said anode comprises a porous base structure with open interstitial crevices, cobalt coating on surfaces of said interstitial crevices and said lithium metal impregnated into said interstitial crevices in contact with said cobalt coating. 
     
     
       2. The improvement of claim 1 wherein said base structure is of an iron alloy and said cobalt coating is bonded to said base structure over essentially all surfaces of said interstitial crevices. 
     
     
       3. The improvement of claim 2 wherein an electrochemical bond affixes said cobalt coating to said base structure. 
     
     
       4. The improvement of claim 1 wherein said base structure comprises a plurality of entangled fibers of iron alloy having coatings of cobalt metal over essentially all outer surfaces and being compacted into a porous structure with a void volume of about 80 to 90%. 
     
     
       5. The improvement of claim 4 wherein said cobalt coating having a thickness in excess of 5% of the diameter of said fibers. 
     
     
       6. The improvement of claim 4 wherein said fibers having diameters of 40 to 60 microns and surface areas of 80 to 120 cm 2  /gram. 
     
     
       7. The improvement of claim 1 wherein said open interstitial crevices being impregnated with molten lithium metal and there being solid lithium-cobalt alloy in wetted contact with said lithium metal on the surface of said cobalt coating. 
     
     
       8. A method of preparing an anode for use within an electrochemical cell including said anode, a cathode and an electrolytic salt, said method comprising cleaning a mass of metallic wool comprising entangled metallic fibers, depositing a cobalt metal coating onto said metallic fibers, compacting said metallic wool to form a porous substrate, and sorbing molten lithium metal onto said porous substrate. 
     
     
       9. The method of claim 8 wherein said metallic wool is steel wool of carbon steel and said depositing of said cobalt coating being performed by electroplating cobalt onto fibers of said steel wool. 
     
     
       10. The method of claim 8 wherein said electroplating is performed onto said metallic wool in an extended condition of 98.5% to 99.5% void volume prior to compacting into a porous substrate having a void volume of 80 to 90%.